2 CA.TALOGUE OF BUTTERFLIES. 



the passage of one of these migratory hordes. An account of it 

 has already appeared in print,* but as it has not often fallen to the 

 lot of an Entomologist to see such an occurrence, it may be worth 

 "while briefly to refer to the matter here. It was a very hot day 

 in July, 1867, and at 9 a.m., when I went to business, I noticed 

 an unusual number of white Butterflies in the street. Lads on 

 their way to school were chasing them, and one or two were 

 always within view. As the day wore on the numbers steadily 

 increased, and by 11 am. a dozen or twenty might have been 

 seen flying down the street, their places being taken by others 

 as they passed on. These, however, were but the advanced 

 guard, the great army was yet to come. By noon they were 

 flying in hundreds, and by two in the afternoon there were 

 thousands of them to be seen at once, all flying in one direction, 

 from east to west. The appearance of such an enormous num- 

 ber of Butterflies all flying at the same time was most extra- 

 ordinary, and attracted the attention of the least observant. 

 When Darwin witnessed a similar flight off the coast of South 

 America, the sailors said it was "snowing butterflies," and no 

 phrase seemed so appropriate for what I saw. Their white 

 colour, and somewhat irregular flight, made them exactly re- 

 semble a heavy fall of large flakes of snow. They continued to 

 pass in undiminished numbers till towards five o'clock, when a 

 sudden thunderstorm and very heavy rain came on. Such of 

 the Butterflies as did not obtain shelter in doorways, window 

 reveils, or under shop cornices, were quickly driven to the 

 ground, where they were pelted to death by the rain, or floated 

 in hundreds along the flooded channels. When the rain ceased, 

 the day was too far advanced for flight to be resumed. I^ext 

 day there was a very large number about the streets, but they 

 flew in a desultory manner, and entirely without the steady, pur- 

 pose-like flight of the day before. I made every possible enquiry 

 as to the origin of this enormous swarm of white Butterflies, but 

 beyond the fact that they appeared to come from the open sea I 

 could not learn anything about them. Fishermen who had been 

 in the bay had noticed them. The sea was perfectly smooth and 



* Young NaturaliBt, Vol. II., p. 29. 



